Here we are, sorry for the delay. I'll go in order to answers:
bdial: thank you, you have reason, the screen is important, what is the best? No-beaded screen are better for deatils? And viewing distance is right: in common house distances are not long, so if you want to see very sharp with medium screen, it's occurs a huge analog resolution.
MattKing: certainly, most of projection lenses are simple triplets, but they are not good, so we need lenses a little bit complex ( for ex. Elmarit pro 150 has some glasses used on 180/2 APO for Leica R.
Agx: yes, yours is excellent tip, we have to also consider the lens damper (another problem...)
Chan Tran: yes, sure, to avoid popping it's need a good cooling system, and to enlarge DOF a variable diaphragm lens
RichardJack: if you use a f8 or 5,6 and the screen is big , is necessary a power projector as simda 3462, Ektapro 9020 with high-light or Carousel 2055 with booster, otherwise slides are too dark.
But anyway, do you know how it can possible to find tests, articles or review of best projection lenses?